853 

Federal Aviation Administration, DOT 

Pt. 43, App. A 

(viii) Elements of an airframe including 

spars, ribs, fittings, shock absorbers, brac-
ing, cowling, fairings, and balance weights. 

(ix) Hydraulic and electrical actuating sys-

tem of components. 

(x) Rotor blades. 
(xi) Changes to the empty weight or empty 

balance which result in an increase in the 
maximum certificated weight or center of 
gravity limits of the aircraft. 

(xii) Changes to the basic design of the 

fuel, oil, cooling, heating, cabin pressuriza-
tion, electrical, hydraulic, de-icing, or ex-
haust systems. 

(xiii) Changes to the wing or to fixed or 

movable control surfaces which affect flutter 
and vibration characteristics. 

(2) 

Powerplant major alterations. 

The fol-

lowing alterations of a powerplant when not 
listed in the engine specifications issued by 
the FAA, are powerplant major alterations. 

(i) Conversion of an aircraft engine from 

one approved model to another, involving 
any changes in compression ratio, propeller 
reduction gear, impeller gear ratios or the 
substitution of major engine parts which re-
quires extensive rework and testing of the 
engine. 

(ii) Changes to the engine by replacing air-

craft engine structural parts with parts not 
supplied by the original manufacturer or 
parts not specifically approved by the Ad-
ministrator. 

(iii) Installation of an accessory which is 

not approved for the engine. 

(iv) Removal of accessories that are listed 

as required equipment on the aircraft or en-
gine specification. 

(v) Installation of structural parts other 

than the type of parts approved for the in-
stallation. 

(vi) Conversions of any sort for the purpose 

of using fuel of a rating or grade other than 
that listed in the engine specifications. 

(3) 

Propeller major alterations. 

The following 

alterations of a propeller when not author-
ized in the propeller specifications issued by 
the FAA are propeller major alterations: 

(i) Changes in blade design. 
(ii) Changes in hub design. 
(iii) Changes in the governor or control de-

sign. 

(iv) Installation of a propeller governor or 

feathering system. 

(v) Installation of propeller de-icing sys-

tem. 

(vi) Installation of parts not approved for 

the propeller. 

(4) 

Appliance major alterations. 

Alterations 

of the basic design not made in accordance 
with recommendations of the appliance man-
ufacturer or in accordance with an FAA Air-
worthiness Directive are appliance major al-
terations. In addition, changes in the basic 
design of radio communication and naviga-
tion equipment approved under type certifi-
cation or a Technical Standard Order that 

have an effect on frequency stability, noise 
level, sensitivity, selectivity, distortion, 
spurious radiation, AVC characteristics, or 
ability to meet environmental test condi-
tions and other changes that have an effect 
on the performance of the equipment are 
also major alterations. 

(b) 

Major repairs

—(1) 

Airframe major repairs. 

Repairs to the following parts of an airframe 
and repairs of the following types, involving 
the strengthening, reinforcing, splicing, and 
manufacturing of primary structural mem-
bers or their replacement, when replacement 
is by fabrication such as riveting or welding, 
are airframe major repairs. 

(i) Box beams. 
(ii) Monocoque or semimonocoque wings or 

control surfaces. 

(iii) Wing stringers or chord members. 
(iv) Spars. 
(v) Spar flanges. 
(vi) Members of truss-type beams. 
(vii) Thin sheet webs of beams. 
(viii) Keel and chine members of boat hulls 

or floats. 

(ix) Corrugated sheet compression mem-

bers which act as flange material of wings or 
tail surfaces. 

(x) Wing main ribs and compression mem-

bers. 

(xi) Wing or tail surface brace struts. 
(xii) Engine mounts. 
(xiii) Fuselage longerons. 
(xiv) Members of the side truss, horizontal 

truss, or bulkheads. 

(xv) Main seat support braces and brack-

ets. 

(xvi) Landing gear brace struts. 
(xvii) Axles. 
(xviii) Wheels. 
(xix) Skis, and ski pedestals. 
(xx) Parts of the control system such as 

control columns, pedals, shafts, brackets, or 
horns. 

(xxi) Repairs involving the substitution of 

material. 

(xxii) The repair of damaged areas in metal 

or plywood stressed covering exceeding six 
inches in any direction. 

(xxiii) The repair of portions of skin sheets 

by making additional seams. 

(xxiv) The splicing of skin sheets. 
(xxv) The repair of three or more adjacent 

wing or control surface ribs or the leading 
edge of wings and control surfaces, between 
such adjacent ribs. 

(xxvi) Repair of fabric covering involving 

an area greater than that required to repair 
two adjacent ribs. 

(xxvii) Replacement of fabric on fabric cov-

ered parts such as wings, fuselages, stabi-
lizers, and control surfaces. 

(xxviii) Repairing, including rebottoming, 

of removable or integral fuel tanks and oil 
tanks. 

(2) 

Powerplant major repairs. 

Repairs of the 

following parts of an engine and repairs of 

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